1. Field of Invention
The device described herein relates generally to the production of oil and gas. More specifically, the present disclosure relates to a system and method of mechanically charging hydraulics and actuating a valve using the hydraulics.
2. Description of Related Art
Valves assemblies are typically provided within wellhead production trees of both surface and subsea wellheads. The valve assemblies are used to control the flow of oil or gas from a wellhead and/or for controlling circulating fluid flow in and out of a wellhead. Most valves include a valve body with an inlet and an outlet, a passage connecting the inlet and outlet, a valve member that slides in and out of the passage for controlling flow through the valve, and a valve stem for handling the valve member. A valve handle is generally coupled to the valve stem. Gate valves and other sliding stem-type valves have a valve member or disc and operate by selectively moving the stem to insert/remove the valve member into/from the flow of fluid to stop/allow the flow when desired.
Some larger valves, or valves having a large pressure differential across the valve member, may require an increased actuating force. These valves may require that a gear train may be included between the handle and the stem. Valve assemblies having a gear or gear train coupled with the valve stem may be powered by a rotating source, where the gear train converts the rotating force into a linear force for sliding the valve stem. Opening and closing wellhead valves can be performed manually by rotating a handwheel or handle, or with an actuator. Electrical actuators may include a motor to provide a rotating source whereas a hydraulic actuator typically includes a piston associated with a pressurized hydraulic fluid for actuating a valve.